The invention relates generally to imaging systems. In particular, the invention relates to an imaging panel for use in a digital x-ray detector.
Non-invasive imaging broadly encompasses techniques for generating images of the internal structures or regions of a person or object that are otherwise inaccessible for visual inspection. For example, non-invasive imaging techniques are commonly used in the industrial field for inspecting the internal structures of parts and in the security field for inspecting the contents of packages, clothing, and so forth. One of the best known uses of non-invasive imaging, however, is in the medical arts where these techniques are used to generate images of organs and/or bones inside a patient which would otherwise not be visible.
One class of non-invasive imaging techniques that may be used in these various fields is based on the differential transmission of X-rays through a patient or object. In the medical context, a simple X-ray imaging technique may involve generating X-rays using an X-ray tube or other source and directing the X-rays through an imaging volume in which the part of the patient to be imaged is located. As the X-rays pass through the patient, the X-rays are attenuated based on the composition of the tissue they pass through. The attenuated X-rays then impact a detector that converts the X-rays into signals that can be processed to generate an image of the part of the patient through which the X-rays passed based on the attenuation of the X-rays. Typically the X-ray detection process utilizes a scintillator, which generates optical photons when impacted by X-rays, and an array of photosensor elements, which generate electrical signals based on the number of optical photons detected.
A significant fraction of the cost of a digital x-ray detector is the imaging panel that contains the two dimensional pixel array composed of light sensitive photo-diodes and field effect transistors (FET)s. This panel is composed of a series of patterned thin film layers deposited on a thin glass substrate using standard semi-conductor processing techniques. Each additional layer adds to the total manufacturing time (cycle time) and the final yield of the detector; and both cycle time and yield add to the total cost of the detector.
One known technique for reducing the cycle time includes processing larger glass substrates, each containing multiple x-ray detectors, which effectively reduces the cycle time. Another known technique for reducing the cycle time includes investing in larger manufacturer capacity. Manufacturers of digital x-ray imaging systems are constantly working on incremental yield improvements via root cause analysis of failure mechanisms and fine-tuning the manufacturing process. Panel and pixel designs are generally chosen based on a trade-off of cost and performance.
A need therefore exists for an imaging panel for use in a digital x-ray detector that reduces both the cost and cycle time associated with the production of a digital x-ray imaging system.